Vehicles normally have a roof supported by a plurality of pillars located between the windows of the passenger compartment of the vehicle. The pillars may be referred to as A, B, C and D pillars. The B-pillar may also be referred to as the center pillar and is disposed between the front door and rear door of the vehicle.
The center pillar provides significant support for the vehicle roof in roll-over tests or “roof crush” tests. The pillars may be formed of thicker material, higher strength material (HSLA steel) and may be provided with additional stamped metal reinforcement parts to improve the results achieved in roof crush tests. The traditional thinking was that roof crush test results are improved by stiffening the pillar assemblies. However, forming pillars with thicker materials and adding stamped reinforcement parts may add substantial weight to the vehicle that is disadvantageous when designing vehicles that must have a reduced weight to achieve increased fuel economy.
Vehicles are also subjected to side impact tests in which a barrier or vehicle is driven into the side of the vehicle. Side impact tests are evaluated based upon the extent of deformation of the side body structure that intrudes into the passenger compartment after the test. Pillars extend downward and laterally outward from the roof and roof rails of the vehicle to the rocker panel assembly. Stiffening the pillars to improve performance as measured in roof crush tests may adversely affect side impact intrusion test results because the portions of the pillars above the vehicle seat may buckle into the upper area of the passenger compartment in the side impact test leading to an unsatisfactory test result.
There is a need to provide a cost-competitive, light weight pillar structure that meets all roof crush test and side impact tests. The pillar structure must also be compact to fit within the design parameters of the available packaging space.
This disclosure is directed to solving the above problems and other problems as summarized below.